/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package axil.vm.output;

import java.io.IOException;
import java.io.Writer;

import static axil.framework.Functions.*;


/**
 * A class providing a metered output stream. When the maximum allowed number of
 * output characters has been exceeded, and exception is raised.
 */
public class MeteredWriter extends Writer {
	private final Writer output;
	private final int max;
	private int actual;


	public MeteredWriter(Writer output, int max) {
		this.output = output;
		this.max = max;
		this.actual = 0;
	}


	/**
	 * Writes a portion of an array of characters.
	 */
	public void write(char[] buffer, int offset, int length) throws IOException {
		actual += length;
		if (actual > max) {
			throw error(axil(), "max-output-exceeded", nv("max", max));
		}
		output.write(buffer, offset, length);
	}


	/**
	 * Flushes the stream.  If the stream has saved any characters from the
	 * various write() methods in a buffer, write them immediately to their
	 * intended destination.  Then, if that destination is another character or
	 * byte stream, flush it.  Thus one flush() invocation will flush all the
	 * buffers in a chain of Writers and OutputStreams.
	 */
	public void flush() throws IOException {
		output.flush();
	}


	/**
	 * Closes the stream, flushing it first. Once the stream has been closed,
	 * further write() or flush() invocations will cause an IOException to be
	 * thrown. Closing a previously closed stream has no effect.
	 */
	public void close() throws IOException {
		output.close();
	}
}
